Java - Display errors in the navigator in eclipse

When I get a syntax error in a source code in Eclipse, I get the usual red cross mark.
Unfortunately some time ago I was used to get the red crosses in the Navigator, very clear to spot the files that contain errors; then I don't know why, now I don't get the errors displayed there, but only inside the source code and in the "Problems view".
Does some one know how to fix this?
Thank you.